CVT Control Device Stepwise Shift Downshift Strategy
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Solution Overview
Problem
In vehicles with continuously variable transmissions, stepwise upshifts can lead to a decrease in driving force as vehicle speed increases, potentially causing the vehicle to lose speed, especially when encountering increased traveling resistance, and simply prohibiting upshifts does not adequately address the driver's acceleration request.
Innovation Solution
A control device and method that perform a downshift control when the accelerator pedal is continuously pressed after prohibiting stepwise shifts, allowing the vehicle to maintain acceleration by downshifting the continuously variable transmission in a stepped manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If stepwise upshift is performed to accelerate the vehicle, then vehicle speed increases, but driving force decreases in a stepped manner causing the vehicle to lose speed
Solution Approach 1:
The control device dynamically adjusts the transmission shift strategy based on real-time driving conditions. When traveling resistance increases (e.g., uphill), the system transitions from stepwise upshift to continuous upshift or prohibits upshift, thereby dynamically optimizing the balance between vehicle speed and driving force to prevent speed loss.
Solution Approach 2:
The control device changes the transmission ratio parameter based on detected driving conditions. By monitoring acceleration requests and traveling resistance, the system adjusts the upshift behavior (prohibiting or enabling it) to maintain appropriate driving force levels while achieving desired acceleration, thus resolving the contradiction between speed increase and force maintenance.
2Force
If stepwise upshift is prohibited to maintain driving force, then acceleration request of the driver cannot be adequately addressed
Solution Approach 1:
The control device continuously monitors the accelerator pedal state and vehicle acceleration response. When the pedal is continuously stepped on after upshift prohibition is activated, the system detects this feedback and responds by performing downshift control, thereby addressing the driver's ongoing acceleration request while maintaining adequate driving force.
Solution Approach 2:
Instead of only allowing upshift, the system inverts the approach by enabling downshift control when upshift is prohibited but acceleration is still requested. This reverse action (downshifting to increase driving force) allows the system to respond to driver acceleration requests even when upshift would be detrimental.
3Force
If downshift control is performed to address acceleration request, then driving force increases, but transmission shifts in opposite direction
Solution Approach 1:
The control device dynamically determines the transmission shift direction based on real-time conditions. When upshift is prohibited but acceleration is requested, the system dynamically switches to downshift control, making the transmission shift pattern adaptive rather than fixed, thereby resolving the contradiction between force increase and shift pattern stability.
Solution Approach 2:
The system prepares for potential driving force insufficiency by having downshift control ready to execute when upshift prohibition is activated. This preliminary preparation ensures that when the driver continues to request acceleration (pedal continuously stepped on), the downshift action can immediately compensate for the lack of upshift, preventing acceleration deficiency.
Data Source
AI summary
A controller includes a control unit configured to perform stepwise shift that upshifts a CVT in a stepped manner to accelerate a vehicle. The control unit performs a downshift control configured to downshift the continuously variable transmission in a case in which an accelerator pedal is continuously stepped on from before prohibition of the stepwise shift to after prohibition of the stepwise shift.